1. Field of the Invention
The invention relates to a manufacturing method of a package structure, and more particularly, to a manufacturing method of a package carrier.
2. Description of Related Art
The purpose of chip package is to protect exposed chips, to reduce contact density in a chip, and to provide good thermal dissipation for chips. A leadframe serving as a carrier of a chip is usually employed in a conventional wire bonding technique. As contact density in a chip gradually increases, the leadframe which is unable to satisfy current demands on the high contact density is replaced by a package carrier which can achieve favorable contact density. Besides, the chip is packaged onto the package carrier by conductive media, such as conductive wires or bumps.
Take a light-emitting diode (LED) package structure commonly used at present time as an example. A LED chip has to be packaged before used, and the LED chip generates a large amount of heat when emitting light. Therefore, if the heat generated by the LED chip cannot be dissipated and keeps accumulating in the LED package structure, a temperature of the LED package structure would keep rising. In this way, the LED chip may be overheated, which causes luminance decay and shortens operating life thereof or even causes permanent damage in server cases.
As the integration level of integrated circuits increases, due to the mismatch of thermal expansion coefficient between the LED chip and the package carrier, the phenomena of thermal stress and warpage become more and more severe, and that causes the reliability between the LED chip and the package carrier to decrease. Therefore, in addition to enhancing the light extraction efficiency, the current package technology focuses on decreasing the thermal stress of the package structure to increase the operating life and the reliability of the package structure.